LED signals vs normal Colour Light Signals.

[TDK]

They've been replacing the old signal lights with these new LED lights for a little while in Victoria, my only problem is they are so bright! You can spot them off from a mile.

I've heared of some train drivers here wearing sunglasses at night because they are so bright.

They've been doing that with traffic lights as well, although there are so many more lights to do though. Do you guys also have traffic lights fitted with LED's?

I doubt it very much any driver would wear sun glasses at night, where did you actually hear this? I think it's an over exagerated comment.

 

[paul1609]

We've had this discussion before.

Without going over ground already well-trod, the brightness of an LED signal does not improve the sighting. There has to be a certain amount of time for a driver to see, identify and correctly respond to a signal aspect. Adding extra aspects with lots of wonderful colours will just be too much complication.

As I've said before, fixed lineside signalling equipment is only good for a maximum of 125mph. If you want to go faster than this you absolutely have to have in-cab signalling. Dreaming up new signal aspects to pad it out from 4 aspects to however many you can work out won't achieve this.

O L Leigh

Cant help but feel that in this day and age manual driving of trains and visual signals should be obsolete. There seem to be huge energy savings from atc.
The driver should have a RTD indicator, start button and emergency stop button.
the days of a visual system and 2 back up safety systems should be long since gone.

 

[jopsuk]

True, paul, but there's not the money to:
1. accelerate the development of the technology to a level where it is acceptable for anything faster and more complex than for example the DLR or an Underground line- needs to be able to cope with very complex timetables (including freiight) and wildly varying train performance envelopes
2. to actually install the system
3. to overcome the massive union opposition there would be the installation of such a system- after all, the job of the "driver" would become much less skilled and presumably suffer a large drop in pay packet.

Really, number 3 is the biggest obstacle.

 

[Aussie_Rail]

I doubt it very much any driver would wear sun glasses at night, where did you actually hear this? I think it's an over exagerated comment.

That's a confirmed fact, even some Policemen asked him at the terminus why he wore them at night. But they are really bright, not sure just how bright they are there but here one LED red signal lights up an entire station when they turn the flood lights off. It's awesome be at when it happens though.

 

[thelem]

Cant help but feel that in this day and age manual driving of trains and visual signals should be obsolete. There seem to be huge energy savings from atc.

The Thameslink Programme will have some automatic operation in the core (in order to allow greater frequency). If that works well and can be economically extended, then I can see the whole line becoming automatically operated in future, but I think the problem will be installing the appropriate signaling along the whole line.

 

[Metroland]

True, paul, but there's not the money to:
1. accelerate the development of the technology to a level where it is acceptable for anything faster and more complex than for example the DLR or an Underground line- needs to be able to cope with very complex timetables (including freiight) and wildly varying train performance envelopes

Not true, many HSR and freight schemes going in worldwide have ATO.

2. to actually install the system

Cost is the biggest issue, it has to be more cost effective than conventional signalling also compatible with a wide range of traction, or traction not fitted with automatic controls. I'm not optimistic about widespread adoption in my lifetime unless something more cost effective and easy to install is found and safety is maintained. Though I have no doubt cab signalling is safer than lineside signalling from the drivers point of view. NR will be replacing lineside signals over the next 40 years, and the cambrian is a testing ground for this.

3. to overcome the massive union opposition there would be the installation of such a system- after all, the job of the "driver" would become much less skilled and presumably suffer a large drop in pay packet.

Really, number 3 is the biggest obstacle.

This would be the biggest problem, though I'm not aware of the RMT objecting to forthcoming introduction of ATO on the jubilee and northern lines. Nor did they object to ATO operation on the central line in the 90s or the Victoria line in 1968. I suspect there is a good case for still having someone sat at the front of the cab and trained in manual operation - indeed Singapore metro is driven manually in the rain.

I'm not entirely convinced that pay packets would be cut. This certainly hasn't happened in the aviation industry, even though planes fly themselves automatically most of the time, indeed is compulsory in certain circumstances. Though that may change as technology improves and there is a cost for cutting back on these posts, having said that I'm not quite the 'optimist' about technology in these circumstances. Humans are naturally very conservative and and even if you could have fully automatic operation of all transport (which I'm not convinced you can at the time of writing) people may want someone at the front, ready to take over. I certainly think there will always be some sort of human presence on trains (and other transport) to stop vandalism and provide assurance.

 

[boing_uk]

They've been doing that with traffic lights as well, although there are so many more lights to do though. Do you guys also have traffic lights fitted with LED's?

Yes we use LED's now that we have overcome some of the technical aspects regards to lamp monitoring. UK regulations require lamp monitoring where pedestrian phases are used - unfortunately controller technology really never kept pace and for many years (including now when upgrading just the lanterns) emulation is required to simulate the load of a halogen lamp as the controller hardware and thus the lamp monitoring was designed for halogen lamps.

It is only in the last couple of years that controllers have been released that can directly monitor LED aspects which is why the uptake of LED traffic signals has been much slower in the UK than the rest of the world.

 

[buz33]

As Fusionrail's said, diodes can only be on or of. Therefore, an LDR or similar would just turn them off at night Not a good idea; I can imagine a rather large increase in SPADs.

I have to disagree with this - LEDs can be dimmed. The light output is dependent upon the amount of current passing through them. Increasing the value of the series resistor will reduce the light output.

 

[sebulba]

Personally, I prefer the new LED's, and I guess they're easier to see in fog, same as the new sytle traffic lights for cars...not everyone's cup of tea, but that's progress

Paul

 

[royaloak]

Well I prefer conventional heads because they are much better at cutting through the fog, and some light reflects back so you can see the signals in the opposite direction which helps you work out where you are.

 

[sebulba]

Well I prefer conventional heads because they are much better at cutting through the fog, and some light reflects back so you can see the signals in the opposite direction which helps you work out where you are.

But surely the same problem appears here using car headlights as an example, take a 10year old car with conventional headlights in fog, and compare them to a modern day Audi with LED's, think there'll be less scatter back from the Audi...just a thought

 

[O L Leigh]

But surely the same problem appears here using car headlights as an example, take a 10year old car with conventional headlights in fog, and compare them to a modern day Audi with LED's, think there'll be less scatter back from the Audi...just a thought

Think or know?

Different light sources make no difference to the fog penetration, whether it's LED or incandescent light. It's all down to the power of the beam.

O L Leigh

 

[90019]

and compare them to a modern day Audi with LED's

They don't use LEDs for the headlights, they're BiXenon
On the front, the LEDs are only used in the DRLs, sidelights and indicators.

take a 10year old car with conventional headlights in fog

If you're driving in the fog, you don't use your headlights unless you don't have front fog lights anyway, because they reflect back off the fog; you use the sidelights and fog lights because the fogs are generally lower and are angled further down to reduce the visible reflections whilst still being visible to oncoming traffic.
(And is why I want to get front fogs for my car)

/pedant

 

[O L Leigh]

If you're driving in the fog, you don't use your headlights unless you don't have front fog lights anyway, because they reflect back off the fog; you use the sidelights and fog lights because the fogs are generally lower and are angled further down to reduce the visible reflections whilst still being visible to oncoming traffic.

No...!!!

Front foglights only illuminate about 4 feet of road. They are hopeless and should not be used instead of dipped headlights. If you rely on the fogs alone you won't be able to see where you are going. About the only benefit they provide is in spreading light further to each side and showing where the verges are. What you need to avoid is using full beam because that just creates a lot of dazzle.

I don't know why it should be, but almost no-one has any idea about the correct or appropriate use of front and rear foglights.

O L Leigh

 

[90019]

Front foglights only illuminate about 4 feet of road. They are hopeless and should not be used instead of dipped headlights. If you rely on the fogs alone you won't be able to see where you are going. About the only benefit they provide is in spreading light further to each side and showing where the verges are. What you need to avoid is using full beam because that just creates a lot of dazzle.

I was talking about when it's daytime, rather than when it's dark.
You don't use them to illuminate the road in front, you use them when it's foggy during the day so that oncoming cars can see where you are (sidelights as well because you have to have them on to use the fogs in most cars).
Substituting them for dipped headlights when it's dark is not a good idea though, as you say because they don't illuminate enough of the road ahead, and using them as well as dipped headlights at night when it's not foggy I find is annoying because it can dazzle others.

 

[O L Leigh]

I was talking about when it's daytime, rather than when it's dark.
You don't use them to illuminate the road in front, you use them when it's foggy during the day so that oncoming cars can see where you are.

OK, I misunderstood. However, even under those conditions I would still be using my dipped headlights as they are at least as visible as fogs.

Misuse of front and rear fogs is a real bugbear of mine. I have been driving for over 15 years and have probably only had to use rear fogs a handful of times. They shouldn't be used indiscriminately as they can dazzle the drivers of following cars, but only when the fog is sufficiently thick and there is nothing immediately behind you. Front fogs are even less useful. My current car has them, as did my previous car, and I have never needed to use them under ANY circumstances.

O L Leigh

 

[Old Timer]

.....You don't use them to illuminate the road in front, you use them when it's foggy during the day so that oncoming cars can see where you are (sidelights as well because you have to have them on to use the fogs in most cars)......

Slight error there Chap ?

Fog lights light up the band of road in front of the car so as to enable you to see the cats eyes, road markings and especially the edge of carriageway markings where provided.

If they are dazzling oncoming cars then they are not angled correctly

 

[90019]

OK, I misunderstood. However, even under those conditions I would still be using my dipped headlights as they are at least as visible as fogs.

When we last had the Haar in over the city - and when I was still using the car with front fogs - (a couple of months ago) I was using the front fogs and sidelights because it was light enough for the headlights to not be required (plus the reflections were quite bad off them).
Mind you, when it was in about 6 months ago, I got a couple of photos of the beams of light from all the lights on the car

(The haar was relatively light at that point)

My current car has them, as did my previous car, and I have never needed to use them under ANY circumstances.

I've had to use both front and back a few times this year, although the haar hasn't come into the city much this year (only 5 or 6 times).

Fog lights light up the band of road in front of the car so as to enable you to see the cats eyes, road markings and especially the edge of carriageway markings where provided.

Yeah, I forgot about that bit.

 

[O L Leigh]

But were you using them correctly...?

O L Leigh

 

[90019]

But were you using them correctly...?

I would say so, it was too light to use the headlights, and the haar was thick enough that the dipped lights were reflecting off it, and you could only see the lights of cars coming towards you and those ahead of you on some of the days as well.

 

[O L Leigh]

Headlights always reflect off fog. However, that doesn't mean that it's time to reach for the fogs.

If you can see the dipped headlights or tail lights of other cars at sensible distances then you have no need to put your own fogs on. This is the test that I use and it has never let me down. I know from experience of seeing other cars whose drivers are using fogs inappropriately that joining in with such behaviour actually negatively affects the safety of both yourself and everyone else. The dazzle created by a car with fogs on when not required is incredible and blots out everything else. Provided that there is no other traffic around I will use my own full beam headlights and dazzle them right back in retaliation in the hope they will turn the offending lights off.

O L Leigh